The present invention relates to a dispenser for dispensing a web of paper towel from a supply roll thereof and, more particularly, to a cut-off mechanism for severing the dispensed portion of the web from the supply roll at the end of a dispensing operation.
A typical prior art paper towel dispenser is disclosed in U.S. Pat. No. 3,408,125 issued to H. Rasmussen on Oct. 29, 1968. In such a dispenser, the user grasps a protruding edge of the towel web and manually pulls it to unwind a length of towel from the supply roll. In the Rasmussen dispenser, after a predetermined length of web has been dispensed, the user pulls the web upwardly against a serrated cutting edge to sever the dispensed web from the supply roll. After cut-off, a time-stop mechanism actuates an internal feed mechanism for advancing the web so as to project the leading end thereof a short distance out of the dispenser for access by the user for the next dispensing operation.
It has been found that the manual tearing-type cut-off utilized in the Rasmussen device was unsuitable because it frequently resulted in uneven or only partial severing of the dispensed web and, frequently, users would prematurely attempt to sever the web before the predetermined length thereof had been dispensed, thereby aborting the operation of the internal feed mechanism. Thus, there was no protruding leading end for the next user to grasp.
This difficulty was somewhat alleviated in dispensers of the type disclosed in U.S. Pat. No. 3,739,965, issued June 19, 1973 to P. W. Jespersen et al. and U.S. Pat. No. 1,449,062, issued on Mar. 20, 1923 to H. E. Schroeder. In both of these latter devices, the web is dispensed between two feed rollers, one of which carries a radially extending cutting knife and the other of which is provided with a radial slot for receiving the knife, so that once during each revolution of the rollers the web will be severed. But in this type of cut-off apparatus, the knife has a tendency to wedge the paper web into the slot rather than cleanly severing it, thereby causing the mechanism to jam.
Other types of gravity or spring-actuated cut-off mechanisms are disclosed in the U.S. Pat. No. 3,221,586, issued to E. B. Bahnsen on Dec. 7, 1965, U.S. Pat. No. 2,333,108, issued to A. P. Krueger et al. on Nov. 2, 1943 and U.S. Pat. No. 345,052 issued July 6, 1886 to H. H. Harrison. But in each of these latter three types of cut-off mechanisms, the movable cutting blade must be cocked, i.e., it is in motion during the dispensing operation. More particularly, the blade must be moved from a starting position in two directions, in one direction to a cocked position and then back through the starting position and in the opposite direction therefrom to the cut-off position. Thus, the distance the blade must travel and the space necessary to accommodate blade travel is unnecessarily large.